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  1. BobK

    PICAXE

    You might find a better response at the PICAXE forum, here: http://www.picaxeforum.co.uk/forum.php Bob
  2. BobK

    Going from prototype to production question.

    Depending on how you are using the several 555s, a small (6, 8 or 14 pin) microcontroller could possibly replace all of the 555's and need fewer external components. I would think the cost would be at least a wash since you can get microcontrollers for less than a dollar. Can you tell us how...
  3. BobK

    Opto-isolator basic question

    Are you sure that will output close to 5V? The configuration is a voltage follower, but the input to the base is optical, so I have no idea what that would do. I wonder if the emitter voltage gets too high it will stop conducting even in the presence of light. Bob
  4. BobK

    help with Joule thief please

    I looked up joule thief, cool project! 1. I assume you meant a 1K resistor, not 1 Ohm, right? 2. Did you connect a battery with the + terminal to the two twisted wires coming out of the torroid and the negative terminal to the emitter of the transistor? 3. Are you sure your LED leads are...
  5. BobK

    Volt and Amps Help!

    A DC to DC converter can increase the voltage supplied by a battery while decreasing the current capacity, is that what you are asking? A voltage source does not supply any specifiic amount of current, it supplies current dependent on the load. Otherwise there would be electrons flying into...
  6. BobK

    Opto-isolator basic question

    That is expected. The output of the opto is an inverter. Bob
  7. BobK

    Voltage Regulating

    For 1.5 ma a linear regulator on the 13V battery is fine. You do not need any additional protection, the sensor will draw only what it needs as long as the input voltage is correct. A 78L05 should work fine and it come in the TO92 package. Bob
  8. BobK

    Help with Laser Alarm Circuit

    Oh, I agree that it is crappy. I was just saying that if you interpret it correctly the circuit might actually work. I suspect the OP wired it wrong due to the bad schematic. Bob
  9. BobK

    LME49811 as a guitar amp.

    I did some looking and I confimed that high voltage high power power supplies are quite expensive. I think your best bet would be to look for a cheap used receiver or amp with the kind of power you will want and take out the power supply from it. Bob
  10. BobK

    LME49811 as a guitar amp.

    Look at the schematic again, it needs dual supplies, i.e. a + and - high voltage supplies. The 5V is not really a problem, this is just a logic input and can be provided by a voltage divider run from the + supply, since it will not require much current. Bob
  11. BobK

    Help with Laser Alarm Circuit

    Actually, there is nothing wrong with that circuit (at least that I can see) once you realize that the large circle with the +9V is intended to mean connect all three wires coming out of it to the positive side of the 9V battery, with the negative side being connected to ground. So, to the...
  12. BobK

    Use USB Thumb Drive to switch a relay

    I have never looked into Arduino. If it has USB host capability, that would probably be a good way to go. Note that host is not the same as device capability. I work with PIC microcrollers and some have only device capability while others have host as well. Bob
  13. BobK

    Use USB Thumb Drive to switch a relay

    That is doable but not exactly simple. You would need a micontroller that has USB host capablitly and a program that would check the flash drive for the software key. Bob
  14. BobK

    DIY Oscilloscope: LCD Controller interchangeability?

    http://www.semifluid.com/?p=15 http://biphome.spray.se/frl_linder/PIC_scope.htm \
  15. BobK

    Is there something to use to flash 2 led lights quickly?

    No, a microcontroller is the best way to go. It can do exacly what the OP asked for, including the hour dealy and blinking the LED only twice, with only a resistor and LED as external components. It would take 3 555 timers and 10 or 15 other components to do the same. Bob
  16. BobK

    Need help with my Plant watering watcher circuit

    Huh? LED current should be in the 5 to 20ma region. You would not be able to see the output of and LED with pA current. Bob
  17. BobK

    Component orientation.

    Hmmm. I would think the drivers themselves would be more likely to deteriorate over 35 years than the electronic components. If they are paper cones, I am surprised that would not have come apart by now. Bob
  18. BobK

    ULN2803A losing voltage

    Why are you putting resistors on the outputs? It is probably these resistors that are dropping the voltage. Bob
  19. BobK

    DIY Oscilloscope: LCD Controller interchangeability?

    2 channels at 5 KHz? This is pretty useless. I would not bother. You can do as well with a PC sound card scope. Bob
  20. BobK

    weird question... i think

    Well, for an antenna to radiate much energy it would need to be about 1/4 the wavelengh. At 20Hz that would be 3750 Km. Bob
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